The invention relates to an apparatus and method for terminating a cable at an item, for example a junction box, to provide a sealed connection therewith.
In many applications it is desired to terminate an electrical cable at a junction box, and to prevent contamination of the interior cf the junction box by sealing the cable where it enters the junction box.
There are two main types of seals for cables passing into junction boxes, namely a seal for a cable which passes through a rigid metal conduit, and a seal for cables which are not within conduits and are relativelY flexible and have at least a flexible protective sleeve. A rigid conduit can usually be sealed in the junction box with conventional 0-rings and threaded connections, and the cable can pass through the conduit and opening in the box without requiring additional sealing on the cable. The present invention is particularly directed to cables having flexible sleeves, such as elastomeric sleeves, or flexible metal armoured sheaths and means of sealing such a cable with a junction box or other item having an opening.
U.S. Pat. Nos. 3,188,380 (Lorenz), 3,285,551 (Tschanz) and 4,358,079 (Navarro) disclose connecting devices associated with an opening of an item, such as a junction box. These devices provide a fluid resistant seal with the cable, and grip the cable compressively to prevent relative movement between the box and cable. In some instances, the grip is sufficient to relieve the electrical conductors within the cable from load when secured to terminals within the box. Such devices have a hollow body which cooperates with the opening, the body having a threaded male portion which receives a threaded hollow cap which is tightened to squeeze onto the cable. These known devices are manufactured for a particular nominal diameter of cable, and can only accommodate small variations from the nominal cable diameter. Consequently, if a wide range of sizes of cattles are to be installed, a corresponding wide range of diameters of connecting devices is required. Furthermore, use of a threaded hollow cap to be screwed onto a body member secured to the item is time consuming and requires care and skill. Under-tightening of the cap car result in leakage through the seal into the box, and over-tightening can result in damage to the assembly, particularly when the cap is fabricated from plastic or other resilient material.
U.S. Pat. Nos. 3,515,798 (Sievert) and 4,389,440 (Keith), both of which are owned by the Minnesota Mining and Manufacturing Company, disclose an elastic cover assembly comprising an elastic cover or sleeve which is sold in an initially stretched condition in which it encloses a removeable rigid spiral core assembly. The spiral core assembly is used as a tool to apply the elastic cover as an insulating sleeve to an electrical cable splice, or other joint between two generally cylindrical workpieces. To apply the cover, the rigid spiral core is uncoiled as a continuous narrow strip through a remaining portion of the spiral core assembly which permits the stretched elastic cover to shrink-fit upon the workpiece joint within the assembly. Both of these last two mentioned patents provide a seal for connected cables or other aligned workpieces.